Toktumi has released Line2 version 3.0 that allows iOS device users to send SMS via VoIP, and over one million SMS text messages have already been sent 4 days after the 3.0 release. Here is more info on Line2 version 3:

Line2 Version 3.0 became the first VoIP app to feature carrier-grade SMS texting, allowing customers to exchange unlimited text messages with any SMS-enabled phone on any carrier. The result is a texting experience that is identical to traditional SMS offered by the major cellular carriers, but at a fraction of the price. Line2 costs $9.95/month for unlimited US/Canada calling and texting. Unlike texting-only applications for the iPhone, Line2 combines VoIP calling capabilities and carrier-grade texting in one app, so that customers can use one number for both types of communication.

Line2 customers get unlimited calling and unlimited SMS texting for half the $20 price that AT&T charges for unlimited texting alone. When you add in the savings achieved by dropping to the lowest AT&T calling plan and using Line2 over Wi-Fi for voice calls, customers can reduce their cell phone bill by as much as $50 per month.

For iPod Touch and iPad users, Line2 turns either device into a Wi-Fi mobile phone with all the features of a traditional cell phone for just $9.95/month. People with regular access to Wi-Fi networks now have a viable alternative to a cell phone for a fraction of the cost. Customers won?t miss calls because they can be forwarded to another phone or sent to voicemail if the device isn?t connected to Wi-Fi.